1. Field of the Invention
Generally, the present invention relates to surgical instruments. More specifically, the present invention relates to trocars that can be used in conjunction with other surgical instruments.
2. Description of Related Art
For many years most surgery was performed using an open field technique. The surgeon made an incision dictated by the need to directly observe the area or field of interest and to insert his or her hand or hands, and/or one or more instruments therein to perform manipulations within the body cavity accessed through the incision. Retractors and assistants help to provide means of access. For many procedures these incisions are as long as 20 centimeters, traumatic, and painful. This translates into a painful recovery, prolonged hospitalization with a slow return to a normal functional state, and significant cost.
An alternative to open surgery, endoscopic surgery, has also been available for many years, though not as widely applied. Through an endoscope, a tubular optical system for viewing the interior of an organ or body cavity, tissues can be observed. An endoscope is used by making a small incision in the appropriate body covering. A hollow tube, or port, usually 10-25 cm in length and 5-30 mm in diameter, is placed through the incision and the endoscope is placed through the hollow tube. Through various other incisions and ports, other instruments can be placed into a body space for manipulation, grasping, cutting, coagulation etc., similar to open surgery. In the abdomen and pelvis, the optical tube is called a laparoscope and the method is referred to as laparoscopic surgery.
Laparoscopic surgery usually includes a step of expanding the body cavity with air, inducing a state of pneumoperitoneum, which enhances the surgeon's view and ability to make manipulations. This is accomplished by one of two techniques, air insufflation or abdominal wall lifting. Abdominal wall lifting creates negative pressure within the cavity in relation to the atmosphere, drawing in air through a small incision when the wall is lifted. The disadvantage with this technique is that observation is imperfect. A tent is created with a central peak and a collapsed perimeter. Though most-structures have midline attachments, most endoscopic manipulations take place in the periphery. This is where visualization with this technique is worst. Insufflation is a positive pressure system using a medicinal vapor such as carbon dioxide or nitrogen injected into the peritoneal cavity to balloon the abdominal wall. Expansion is more uniform; vision is better. This is the most widely used technique. Because of the positive pressure, however, the abdomen must be sealed to maintain expansion. This requires that all incisions and ports be sealed. Insufflation also has adverse respiratory and hemodynamic consequences due to positive pressure inhibiting chest expansion and venous blood return to the heart.
Though endoscopic surgery has been available for many years, its application has recently increased due primarily to the development of video monitoring equipment. This has allowed all members of the surgical team to observe, though indirectly, what only the surgeon could previously observe through a laparoscope. In some cases visualization is better than with direct observation. This has led to renewed interest and investigation of these techniques.
The benefit of endoscopic surgery is the limited incisional trauma, improved cosmesis, and decreased pain. For several simple techniques, such as laparoscopic cholecystectomy, this has translated into decreased hospitalization and earlier return to normal function, though cost savings is debated.
While some open surgical procedures have been adapted to laparoscopic technique, there are limitations with this method, particularly with more complex procedures. Fundamental problems relate to the access tubes used for inserting the various manipulative instruments. While limiting incisional trauma, the small diameter of these tubes dictates and limits the design of the inserted instruments. To achieve similar function as in open surgery, equipment becomes complex and therefore more expensive. There is also added risk with each access tube. Each tube requires a stab-wound of the body wall, risking injury to contained viscera with each puncture.
Equally important has been the impact on the surgeon's ability to manipulate tissue. While the visual field may have been improved, tactile sensation, depth perception, and proprioceptive awareness of tissues have been markedly reduced by instruments that insulate the surgeon from the operative field. As the surgeon continually confirms that that which is done is that which is desired, procedural and anesthesia time increase. Furthermore, the limited access enabled by each port dictates that multiple ports be used. As procedural complexity increases, the surgeon must adapt to a continuously changing and less predictable environment than with simple procedures. The number of ports, and the risk and incidence of complications increases. The requirement for highly skilled and coordinated surgical teams also increases. This has resulted in long learning curves and has limited wide application of these procedures for complex cases.
One device in common usage to establish relatively small incisions for the insertion of equipment therethrough is the trocar. The trocar has a sharp end designed to pierce the skin as the surgeon presses it down to pierce through the skin. It may also pierce the underlying viscera unless great care is taken, particularly in view of the flexibility of the body wall. The trocar includes a cannula or tube used for drainage or for the insertion of a device into the body cavity. Since it is desirable to minimize the patient's wounds, there is an effort made to minimize the size of an incision associated with trocar use. As a result, the size of the tube used in the trocar-created incision is generally relatively small. It therefore can only be used to pass relatively small devices into the body cavity. Moreover, the narrow tube severely restricts maneuverability of the device contained therein. Therefore, though trocars offer the advantage of wound minimization, they are of some danger to the viscera, they are of restricted dimensions for allowing the passage of devices of interest there through, and they permit limited tactile manipulation.
There has been concern about wound contamination during laparoscopic surgery, particularly the implantation of tumor cells. The etiology of this problem is unclear. It may be a systematic problem with a particular element of the technique, such as insufflation where positive pressure venting through the incision results in contamination. Another systematic problem might be direct contamination during specimen removal. The anecdotal occurrence of these problems suggests a more isolated and less systematic error, such as poor tissue handling technique. However, these concerns and the lack of understanding have limited the application of the technique.
It would therefore be useful to develop a surgical instrument that enables endoscopy to be utilized in more delicate surgeries. More specifically, it would be useful to develop an instrument that enables endoscopy to be used without concern for contamination of the tissue wherein the surgery is being performed. For example, major heart surgery has been accomplished by procedures that require full cardiopulmonary bypass (CPB), and complete cessation of cardiopulmonary activity. Open-heart surgery typically requires significant hospitalization and recuperation time for the patient. The average mortality rate with this type of procedure is low, but is associated with a complication rate that is often much higher compared to when cessation and CPB are not required. While very effective in many cases, the use of open-heart surgery to perform various surgical procedures such as coronary artery bypass grafting (CABG) is highly traumatic to the patient. These procedures require immediate postoperative care in an intensive care unit, a period of hospitalization for at least several days, and an extended recovery period. In addition, open-heart procedures require the use of CPB, which continues to represent a major assault on a host of body systems. For example, there is noticeable degradation of mental faculties following such surgeries in a significant percentage of CABG patients. This degradation is commonly attributed to cerebral arterial blockage and emboli from debris in the blood generated by the use of CPB during the surgical procedure. At the same time, the dramatic increase in the life expectancy of the general population has resulted in patients that are more likely to be older and in poor health, with less cardiovascular, systemic, and neurologic reserve needed to recover from the trauma caused by the use of CPB. As a consequence, inflammatory, hemostatic, endocrinologic, and neurologic stresses are tolerated to a much lesser degree by a significant number of patients today, and play a more significant role in CPB-induced morbidity.
The CABG procedure generally involves open chest surgical techniques to treat diseased vessels. During this procedure, the sternum of the patient is cut in order to spread the chest apart and provide access to the heart. During surgery the heart is stopped, and by the use of CPB, blood is diverted from the lungs to an artificial oxygenator. During CABG procedures, a source of arterial blood is connected to a coronary artery downstream from the occlusion. The source of blood is often an internal mammary artery, and the target coronary artery is typically among the anterior or posterior arteries, which may be narrowed or occluded. The same or similar CPB procedure is used in conjunction with other cardiac surgical procedures, such as value repair or replacement and heart transplant.
The combined statistics of postoperative morbidity and mortality continue to illustrate the shortcomings of CPB. The extracorporeal shunting and artificially induced oxygenation of blood activates a system wide roster of plasma proteins and blood components in the body including those that were designed to act locally in response to infection or injury. When these potent actors are disseminated throughout the body without normal regulatory controls, the entire body becomes a virtual battleground. The adverse hemostatic consequences of CPB also include prolonged and potentially excessive bleeding. CPB-induced platelet activation, adhesion, and aggregation also contribute to depletion in platelet number, and are further compounded by the reversibly depressed functioning of platelets remaining in circulation. The coagulation and fibrinolytic systems both contribute to hemostatic disturbances during and following CPB. However, the leading cause of morbidity and disability following cardiac surgery is cerebral complications. Gaseous and solid micro and macro emboli, and less often perioperative cerebral hypoperfusion, produce neurologic effects ranging from subtle neuropsychologic deficits to fatal stroke. Advances in computer tomography, magnetic resonance imaging, ultrasound, and other imaging and diagnostic techniques have added to the understanding of these complications. But with the possible exception of perioperative electroencephalography, these technologies do not yet permit real time surgical adjustments that are capable of preventing emboli or strokes in the making. Doppler and ultrasound evaluation of the carotid artery and ascending aorta, and other diagnostic measures, can help identify surgical patients at elevated risk for stroke and are among the growing list of pharmacologic and procedural measures for reducing that risk.
CPB also affects various endocrine systems, including the thyroid gland, adrenal medulla and cortex, pituitary gland, pancreas, and parathyroid gland. These systems are markedly affected not only by inflammatory processes, but also by physical and biochemical stresses imposed by extracorporeal perfusion. Most notably, CPB is now clearly understood to induce euthyroid-sick syndrome that is marked by profoundly depressed triiodothyronine levels persisting for days following cardiothoracic surgery. The efficacy of hormone replacement regimens to counteract this effect, are currently undergoing clinical investigation. By contrast, levels of the stress hormones epinephrine, norepinephrine, and cortisol are markedly elevated during and following CPB, and hyperglycemia is also possible.
Alternatives to CPB are limited to a few commercially available devices that may further require major surgery for their placement and operation such as a sternotomy or multiple anastomoses to vessels or heart chambers. For example, some present day devices used in CPB may require a sternotomy and an anastomosis to the ascending aorta for placement. The main drawbacks of these devices include their limited circulatory capacity, which may not totally support patient requirements, and their limited application for only certain regions of the heart, such as a left ventricular assist device. Other available devices that permit percutaneous access to the heart similarly have disadvantages, such as their limited circulatory capabilities due to the strict size constraints for their positioning even within major blood vessels. Moreover, the relative miniaturization of these types of devices present a high likelihood of mechanical failure. In further attempts to reduce the physical dimensions for cardiac circulatory apparatus, the flow capacity of these devices is significantly diminished.
During cardiac surgery, the heart is either beating, in which case the heart continues to circulate the blood through the lungs to maintain the patient, or immobilized entirely in which case oxygenation and circulation of blood to maintain the patient requires use of CPB. Bypass surgery on a beating heart has been limited to only a small percentage of patients requiring the surgical bypass of an occluded anterior heart vessel. These patients typically could not be placed on CPB and were operated on while the heart was kept beating. These patients are at risk of having to be placed on CPB on an emergency basis in the event the heart stops or becomes unstable or is damaged during the surgical procedure on the beating heart. Meanwhile, patients requiring surgery on posterior or lateral heart vessels and whose hearts must be immobilized and placed on CPB often suffer major side effects as previously described.
The medical community is currently performing more beating heart bypass surgery in an effort to avoid the use of artificial heart-lung machines. The need is increasing for apparatus systems, methods and associated equipment to enhance the capability and versatility of beating heart surgery and to avoid CPB procedures in any heart surgery. The current trend toward thoracoscopic methods of performing bypass surgery, without opening the chest cavity, have resulted in limited success and applicability primarily due to the limited number of heart vessels which can be accessed through thorascopic methods. A major limitation of thorascopic bypass surgery methods is due to the fact that only the anterior heart vessels are accessible for surgery. More importantly, even open chest surgery providing full access to the heart also requires CPB when bypass surgery is performed on the lateral or posterior vessels of the heart, due to the fact that in conventional procedures the heart must be stopped when it is lifted or rotated from its normal position and manipulated for surgical access to the various heart vessels. Obviously, the heart is also stopped when valve repair or replacement is performed and when heart transplant is performed.
Further, tens of thousands of people are born each year with congenital defects of the heart. Some of the more common types of congenital cardiac defects include atrial septal defect (ASD), ventricular septal defect (VSD), and patent ductus arteriosis (PDA). An ASD is a hole in the cardiac septum between the left and right atria, while a VSD is a hole in the septum between the left and right ventricles. Patent ductus arteriosis is incomplete closure of the opening between the pulmonary artery and the aorta that is present during fetal development. These conditions may cause blood to abnormally shunt from the right side of the heart to the left side of the heart without being properly oxygenated in the lungs, so that the body tissues supplied by the blood are deprived of oxygen. In addition, blood in the left side of the heart may shunt back to the right side through the defect rather than being pumped into the arterial system, causing abnormal enlargement of the right chambers of the heart.
ASD's, VSD's and PDA can frequently be surgically repaired with significant success. Smaller defects may be repairable by simply suturing the defect closed, while larger defects may require a patch of polyester, expanded polytetrafluoroethylene, or a portion of the patient's own pericardium to be sutured into the heart to cover and occlude the defect.
Ordinarily, such surgery is performed using open-chest techniques while the heart is under cardioplegic arrest and circulation is maintained by cardiopulmonary bypass. Using such techniques, a gross sternotomy or thoracotomy is created in order to gain access to the heart and great vessels, facilitating clamping and cannulation of the aorta for inducing cardioplegic arrest, and allowing instruments to be introduced into the chest cavity and into the heart to perform the surgical repair. The necessity of stopping the heart significantly heightens the risks attendant such procedures, particularly the risks of causing ischemic damage to the heart muscle, and of causing stroke or other injury due to circulatory emboli produced by aortic clamping and vascular cannulation. In addition, the creation of a gross thoracotomy produces significant morbidity and mortality, lengthens hospital stay and subsequent recovery, increases costs, and worsens the pain and trauma suffered by the patient. Moreover, many congenital defects are repaired in children under the age of ten years for whom the morbidity and mortality of open-chest surgery and cardioplegic arrest can be even greater than for older patients.
In an effort to avoid the necessity of grossly opening the chest and stopping the heart, a number of intravascular devices have been developed for repair of ASD's, VSD's, and PDA. For example. U.S. Pat. No. 3,874,388 to King et al. discloses an intravascular delivery catheter introduced intraluminally from a peripheral vein into the right side of the heart which can be used to position an artificial umbrella-like patch across a septal defect and to anchor the patch to the cardiac septum. Other intravascular delivery devices and artificial patches for the repair of septal defects can be seen in U.S. Pat. No. 5,334,217, U.S. Pat. No. 5,284,488, U.S. Pat. No. 4,917,089, U.S. Pat. No. 4,007,743, and PCT Application No. PCT/US92/10141.
While intravascular approaches to the repair of congenital defects can provide certain advantages, the most significant of which is the elimination of the need for gross thoracotomy and cardioplegic arrest, these techniques have suffered from a number of problems. One such problem is the difficulty in manipulating the artificial patches into position across a defect using only the proximal end of a long and flexible delivery catheter positioned through a tortuous right lumen. Also problematic is the inadequacy of fixation of endovascularly-placed patches, creating a tendency of such patches to migrate or embolize after placement, which can allow blood to again shunt through the defect. In addition, once such a patch has been placed and the delivery catheter detached from the patch, relocating and repositioning the patch with the catheter is difficult, if not impossible, and may require open surgical correction. Moreover, in young children, the size of the peripheral vessels is extremely small, and damage to such vessels could have serious effects upon the growth of the child. Thus, the size of the devices that can be introduced through such vessels is greatly limited.
In addition to ASD, VSD, and PDA, various other types of cardiac disease also may be diagnosed and treated by intervention within the interior chambers of the heart. For example, some cardiac arrhythmias such as ventricular tachycardias, supraventricular tachycardias, and atrial fibrillation, may be diagnosed by obtaining access into an interior chamber of the heart and by performing electrophysiological mapping to identify abnormal conduction pathways. Once these abnormal conduction pathways are identified, in some cases the disease may be treated by ablating selected cardiac tissue using radiofrequency (RF) energy or a medical laser to eliminate the abnormal pathways. A number of endovascular approaches have been developed which attempt to allow intracardiac mapping and ablation using catheters introduced transluminally from peripheral vessels into the heart. Such devices are disclosed, for example, in U.S. Pat. Nos. 4,960,134, 4,573,473, 4,628,937, and 5,327,889. However, endovascular mapping and ablation devices suffer from many of the same problems suffered by endovascular septal defect repair devices, including a lack of control and precise positionability from the proximal end of these highly flexible and elongated devices, the significant size constraints of peripheral vessels, and the inability to position the devices in all potentially diseased sites within the heart.
What are needed, therefore, are devices and methods to enable the repair of ASD, VSD, PDA, and other congenital defects, as well as cardiac arrhythmias and other diseases of the heart, which eliminate the need for gross thoracotomy and cardioplegic arrest, but which overcome the aforementioned problems with intravascular techniques. The devices and methods should facilitate a high level of control for precise manipulation within the heart. The devices and methods should produce a septal defect or PDA repair that is reliable and long-lasting, and should not be susceptible to migration, embolization, or reopening of a defect. The devices and methods for septal defect and PDA repair should allow the position of a repair patch to be inspected after initial placement and to be repositioned if necessary. Finally, the devices and methods should not risk damaging the peripheral vessels of the patient, nor should the size and configuration of the devices be limited by the size of the patient's peripheral vessels.